Could you be converted to glacier seismology?! Join our group at Leeds’ School of Earth and Environment, collaborating with the British Antarctic Survey, to apply seismic methods - from field survey through to interpretation - to some of the most pressing issues in glaciology today! Full project description here: https://www.nercdtp.leeds.ac.uk/projects/index.php?id=800
Rationale and Motivation
Significant research effort is directed towards improving forecasts of glacier dynamics and their associated impacts on sea-level rise, particularly for ice masses on the Antarctic continent. Innovative methodologies are required if we are to fully capture the physics of the glacier system. The study sites considered in this project are critical for the stability of two Antarctic regions:
- Korff Ice Rise, which influences the dynamics of the vast Filchner-Ronne Ice Shelf, and
- Thwaites Glacier, considered to be the vulnerable pinning-point of the West Antarctic Ice Sheet.
Improved insight at these stability-critical sites will benefit subsequent models for assessment of entire regions of Antarctic ice dynamics.
Stability is influenced by internal ice properties (e.g., water content, temperature) and the characteristics of the material immediately beneath the glacier bed. These properties can be quantified using seismic reflection methods: ice temperature is related to seismic attenuation, and amplitude-versus-offset (AVO) methods allow the physical properties of the subglacial environment to be diagnosed. However, these methods are typically applied only for the compressional (P-) wave component of the seismic wavefield, and other components are often overlooked. The value of mode-converted reflections (i.e., energy that impinges on an interface as a P-wave, but excites shear (S-) wave particle motion) is yet to be explored, but could offer a valuable source of constraint for quantitative assessments of physical ice properties.
• Quantitative seismic analysis holds the key to establishing the mechanical properties of glaciers – the very properties which are required to accurately parameterise predictive models of glacier dynamics.
• Global sea levels are predicted to rise by ~1 m over the next 100 years, but such estimates are uncertain. Improved predictions require a comprehensive description of all aspects of the glacier system.
• Seismic surveys are a powerful means of accessing the deep, dynamic underbelly of an ice mass. Hitherto, converted-wave seismology has been largely overlooked but could offer a new source of valuable interpretative insight.
• This project explores the scope of converted-wave seismology to quantify fundamental glaciological properties. Test data will be acquired by the student on Norway’s Hardangerjøkulen ice cap with existing datasets provided at two priority Antarctic sites.
• The successful development of converted-wave methodologies will broaden the glaciological seismic toolbox, providing novel insight at sites of current research interest.
Aim and Objectives
With the overall aim of exploring the scope, potential and added-value of converted-wave methods in glacier seismology, you will work towards the following objectives:
1) Assess and test the criteria for reliable acquisition of converted-wave reflections, at a test site at Hardangerjøkulen;
2) Undertake an analysis of compressional- and converted-wave characteristics (AVO, but potentially extending to attenuation and velocity) at two Antarctic sites;
3) Provide a comprehensive interpretation of the englacial and subglacial material properties at Korff Ice Rise and Thwaites Glacier, drawing on your novel converted-wave methodologies;
4) Recommend ‘best practice’ for the application of converted-wave methodologies at wider glaciological survey sites.